Hydrophone module

ABSTRACT

An assembly with a first coupling having a forward bulkhead device is provided. The forward bulkhead device contains a first connector insert having first end connections for wires and optical fibers of an acoustic array. The assembly also includes a second coupling having an aft bulkhead device therein. The aft bulkhead device contains a second connector insert having second end connections for the wires and optical fibers of the acoustic array. The forward bulkhead device further includes an alignment assembly. The alignment assembly is matable with the aft bulkhead device to align the first connector insert with the second connector insert. The forward bulkhead device further includes a locking ring connecting the forward bulkhead device with the aft bulkhead device.

The present application is a divisional non-provisional applicationwhich claims the benefit of previously-filed U.S. patent applicationSer. No. 17/015,144 filed on Sep. 9, 2020 and entitled “Thin Line TowedArray Bootable Bulkhead” by the inventors Eric H. Kirchoff and MichaelJ. Kroger.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States of America for any governmentalpurpose without payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention is directed to towed array modules and moreparticularly, to bootable bulkhead assemblies for joining modulararrays.

(2) Description of the Prior Art

Arrays of hydrophones are towed for sensing sound below the surface ofthe ocean. Typically, such arrays are linear assemblies of modules witheach module having sections that have a bulkhead at opposing ends.

Hydrophones are mounted in the sections. Sound pressure waves in theocean pass through the wall of various sections where the hydrophonessense the pressure fluctuations and transform the sensed pressures intoelectrical signals which are transmitted back to a support vessel.

Submarines can deploy a thin-line towed-array (TLTA) using mechanicalhandling systems. Each module of the thin-line array includes an outersheath or hose that contains the hydrophones and supporting electronics.However, TLTAs have historically had poor reliability. One of thereasons for this poor reliability is the mechanical stress on theelectrical and optical data paths during booting of the array module.

Booting is the process of pulling a pre-hose assembly into the hose tocreate the final module assembly. The pre-hose assembly includeselectrical and optical harnesses, telemetry units, internal strengthmembers and other components that constitute functional elements alongwith strength members to carry tension across each array module.

To pull the pre-hose assembly into the hose of the TLTA module, the hoseis inflated beyond a nominal, non-pressurized inner diameter in order toreduce friction between the pre-hose assembly and the inside wall of thehose.

Typically, bulkheads at the end of each module are too large to fitthrough the ends of the hose; therefore, each end of the pre-hoseassembly is terminated with a coupling. However, one end of the pre-hoseassembly may be constructed without the wires and optical fibersterminated into the connector insert and coupling. This end is pulledinto the hose first and to the other end of the hose until theterminated end of the pre-hose assembly is seated in the coupling.

Once the first end of the pre-hose assembly is seated in the coupling;the other end of the pre-hose assembly is terminated in the connectorinsert and bulkhead. In order to make this happen, an excess length ofwire and fiber is needed free from the hose to terminate the second end.As a result, the pre-hose assembly is longer than the hose.

The hose is then elongated over the pre-hose assembly until the otherend of the unseated bulkhead is seated in the coupling. Occasionally,final sections of the pre-hose assembly are reinserted into the hose byhand. In either case, the wires and fibers in the excess pre-hoseassembly may wrinkle and fold inside the hose; thereby, subjecting thewires and fibers to stresses that contribute to poor reliability.

SUMMARY OF THE INVENTION

Devices and methods described herein allow for the booting of a thinline towed array with connector inserts prepopulated inside a bulkhead.Wires and fibers are pre-terminated in the connector insert and bulkheadbefore the booting process. This pre-termination eliminates the need topull excess pre-hose material through the hose.

It is anticipated that the pre-hose can be shortened in relation to thehose such that both bulkheads can be seated at the same time; thereby,reducing wire and fiber stresses introduced through excess lengths andpulling back into the hose. Since some frictional buildup will remainbetween the pre-hose assembly and the hose walls; excess length may berequired to account for hose stretch caused by induced tension from thefriction. Furthermore, the TLTA bulkhead enables a booting process thatreduces stress on the electrical and optical data paths in the array.

The TLTA bulkhead disclosed herein is novel in the capability to bebooted with the optical and electrical connectors already terminated inthe connector inserts and the connector insert installed in thebulkhead. This reduces the amount of pre-hose assembly, or towed arrayinternals, which must be pulled past the booting process. This alsoreduces the excess pre-hose length requirement and improves towed arrayreliability by reducing stresses on the optical and electricalcomponents and wiring.

According to another aspect of the invention, an assembly has a firstcoupling having a forward bulkhead device therein. The forward bulkheaddevice contains a first connector insert having first end connectionsfor wires and optical fibers of an acoustic array. The assembly alsoincludes a second coupling having an aft bulkhead device therein. Theaft bulkhead device contains a second connector insert having second endconnections for the wires and optical fibers of the acoustic array.

The forward bulkhead device further includes an alignment assembly. Thealignment assembly is matable with the aft bulkhead device to align thefirst connector insert with the second connector insert. The forwardbulkhead device includes a locking ring to connect with the aft bulkheaddevice.

According to an exemplary hydrophone assembly herein, a housing tubecomprises an elongated sleeve having a first end and a second end. Apre-tube assembly is located inside the housing tube. The pre-tubeassembly includes a plurality of hydrophones, and a harness connected tothe hydrophones.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome apparent upon reference to the following description of thepreferred embodiments and to the drawings, wherein correspondingreference characters indicate corresponding parts throughout the severalviews of the drawings and wherein:

FIG. 1 is a sectional view of a towed array system of the presentinvention;

FIG. 2 is a cross section view of an aft bulkhead assembly of thepresent invention;

FIG. 3 is a cross section view of a forward bulkhead assembly of thepresent invention;

FIG. 4 is a cross section view of a bootable bulkhead of the presentinvention;

FIG. 5 is a perspective view of an alignment assembly of the presentinvention;

FIGS. 6A and FIG. 6B are end views of an alignment assembly and forwardbulkhead device of the present invention;

FIG. 7 shows an end view of the alignment piece on the aft bulkheaddevice of the present invention;

FIG. 8 is an end view of an aft bulkhead device of the presentinvention;

FIG. 9 is a cross section view of a female clevis of

the present invention;

FIG. 10 illustrates the tensile load path across the bootable bulkhead;and

FIG. 11 is a flow chart illustrating methods herein.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, FIG. 1 shows a towed array 100. The towedarray 100 contains a linear series of modules 102 in which the modulescouple together. The array 100 is towed from a vessel 104, such as asurface ship or a submarine, using a cable 106.

Each of the modules 102 has a housing formed by a flexible hose 108. Theflexible hose 108 may be made from an elastomer or plastic and may bereinforced, such as with Kevlarm fibers or other suitable fibers. For athin-line towed array, the hose section for each module 102 willtypically be one and one-half inch or less in diameter and have a lengthof 30 to 250 feet. The relative dimensions of the modules 102 aredistorted in FIG. 1 for illustration purposes.

Hydrophones 110 are disposed in each of the modules 102. A plurality ofmodules 102 may be coupled together to form the array 100. Thehydrophones 110 communicate via a harness 112 inside the flexible hose108, which is connected to a transmission line 114 inside the cable 106.

Sound pressure waves in the ocean pass through the wall of variousmodules 102 where the hydrophones 110 sense the pressure fluctuationsand transform the sensed pressures into signals that are transmitted viathe cable 106 back to the vessel 104. The transmission line 114 may bean electric and/or optical conduit for relaying signals from the array100 via the harness 112 to the vessel 104. The signals are thenprocessed to provide a representation of the underwater sound.

The flexible hose 108 for each module has a first end 116 and a secondend 118, referred to herein as the forward end (corresponding to 116)and the aft end (corresponding to 118). Typically, the ends of themodules 102 are sealed at each of opposing ends by a connector 120. Theconnector 120 is constructed of two halves, which will be described indetail below.

The connector 120, referred to herein as the Bootable Bulkhead includesforward and aft couplings and forward and aft bulkheads. The harness 112can be attached to the bulkheads. The connectors 120 permit mating ofadjacent modules 102 and allow the signals from the hydrophones 110 topass therethrough as if the harness 112 were continuous.

As mentioned above, each module 102 for a towed array 100 is formed bypulling a pre-hose assembly into the flexible hose 108 to create a finalassembly. The pre-hose assembly comprises the hydrophones, electricaland/or optical harnesses, telemetry units and other components thatconstitute the functional elements of each module 102. To pull thepre-hose assembly into the flexible hose 108; the flexible hose isinflated beyond a non-pressurized inner diameter. Typically, bulkheadsat the end of each module 102 are too large to fit through the ends ofthe flexible hose 108; therefore, each end of the pre-hose assembly isterminated with a coupling.

However, one end of the pre-hose assembly may be constructed without thewires and optical fibers terminated into the connector insert andcoupling. This end is pulled into the flexible hose 108 first andthrough to the other end of the flexible hose until the terminated endof the pre-hose assembly is seated in the coupling.

Once the first end of the pre-hose assembly is seated in the coupling;the other end of the pre-hose assembly is terminated in the connectorinsert and bulkhead. In order to make this happen, some excess length ofwire and fiber is needed free from the flexible hose 108 to terminatethe second end. The flexible hose 108 is then elongated over thepre-hose assembly until the other end of the unseated bulkhead is seatedin the coupling.

As mentioned above, the connector 120 is constructed of two halves, theaft bulkhead assembly and the forward bulkhead assembly, which reside onthe aft and forward ends of each array module 102, respectively. FIG. 2shows a section view of an aft bulkhead assembly 202. The aft bulkheadassembly 202 includes an aft coupling 204, an aft bulkhead device 206,an aft connector insert 208, and a female clevis 210.

The aft connector insert 208 is housed within the aft bulkhead device206. By design, the aft bulkhead assembly 202 is not bootable, andtherefore cannot be pulled through the aft coupling 204 or the flexiblehose 108. The aft bulkhead assembly 202 is assembled prior to booting ofthe module 102.

While the aft bulkhead assembly 202 comprises three main components,various hardware components, such as O-ring grooves 212 in the aftbulkhead device 206, along with the one or more O-rings 214 may beprovided to seal the aft bulkhead device against a mating surface 216 onthe aft coupling 204. The aft end of the wires and optical fibers (notshown) of the harness 112 terminate in the aft connector insert 208. Theaft end of the internal strength members (not shown) for the module 102terminate to the female clevis 210. Once seated in the aft coupling 204,the aft bulkhead assembly 202 is held in place using radial screws (notshown) or other fasteners.

FIG. 3 shows a section view of a forward bulkhead assembly 302. Theforward bulkhead assembly 302 includes a forward coupling 304, a femaleclevis 306, a forward connector insert 308, and a forward bulkheaddevice 310. The forward connector insert 308 is housed within theforward bulkhead device 310. In a mirror view to the aft bulkheadassembly 202, the forward end of the wires and optical fibers (notshown) of the harness 112 terminate in the forward connector insert 308and the forward end of the internal strength members (not shown) for themodule 102 terminate to the female clevis 306.

The outer diameter of the forward bulkhead device 310 is smaller thanthe inner diameter of the forward coupling 304. Given that the outerdiameter of the forward bulkhead device 310 is smaller than the innerdiameter of the forward coupling 304; the forward bulkhead device 310can be booted through the forward coupling 304 and the flexible hose 108when the flexible hose is inflated.

The forward bulkhead assembly 302 can be pulled clear of the flexiblehose 108. Since the wires and optical fibers have been terminated in theforward connector insert 308 and the forward connector insert iscontained in the forward bulkhead device 310; the pre-hose assembly doesnot need to be pulled far out of the flexible hose 108.

The forward bulkhead assembly 302 also includes a sealing sleeve 312that can be pushed over the outside of the forward bulkhead device 310after the sleeve has been pulled through the flexible hose 108. Alocking ring 314 is slid over the sealing sleeve 312 and screwed ontothe forward bulkhead device 310. The locking ring 314 has standardthreads to mate with the aft bulkhead assembly 202.

The sealing sleeve 312 is inserted around the forward bulkhead device310 to seal the bulkhead to environmental conditions. The sealing sleeve312 also acts as a centering ring to allow the forward bulkhead device310 to remain centered in the forward bulkhead assembly 302.

The forward bulkhead assembly 302 may also include hardware components,such as O-ring grooves 316 in the forward bulkhead device 310, alongwith the one or more O-rings 318 provided to seal the forward bulkheaddevice 310 against a mating surface 320 on the sealing sleeve 312. Inaddition, other O-ring grooves 322 in the sealing sleeve 312, along withthe one or more O-rings 324 may be provided to seal the sealing sleeve312 against a mating surface 326 on the forward coupling 304.

Each module 102 includes a forward bulkhead assembly 302 on the firstend 116 and an aft bulkhead assembly 202 on the second end 118. Thearray 100 is constructed by attaching the first end 116 of a module 102to the second end of another module 102.

FIG. 4 shows the connector 120 (Bootable Bulkhead) with the aft bulkheadassembly 202 of a first module mated to the forward bulkhead assembly302 of a second module. As shown in the figure, a portion 402 of the aftbulkhead device 206 fits within the locking ring 314 and a portion 404of the aft connector insert 208 fits within the forward bulkhead device310, such that a distal end 406 of the aft connector insert 208 abuts adistal end 408 of the forward connector insert 308 to form a matingjunction.

Referring again to FIG. 3 , in order to ensure proper alignment of theforward bulkhead assembly 302 with the aft bulkhead assembly 202; theforward bulkhead assembly includes a retained shoulder 328 that isthreaded onto the forward bulkhead device 310. The retained shoulder 328provides a bearing surface for the locking ring 314 and an alignmentassembly 502, such as shown in FIG. 5 .

The alignment assembly 502 includes an alignment ring 504 with alignmentpins 506 extending perpendicular to the alignment ring 504 and a notchedkey 508. The alignment assembly 502 preserves radial alignment betweenthe modules 102. It is important to preserve radial alignment betweenthe modules 102 in order to align fiber and electrical pins within theaft connector insert 208 and the forward connector insert 308.

A plurality of set screws 330 are used in the alignment assembly 502.The set screws 330 are installed through the locking ring 314 andapertures 510 in the alignment ring 504 to prevent the alignmentassembly 502 from falling off during mating of the forward bulkheadassembly 302 with the aft bulkhead assembly 202. The set screws 330 alsoprevent the retained shoulder 328 from vibrating off and breaking theinter-module connection. Similarly, a locking tab 332 may be used toprevent the locking ring 314 from vibrating loose. The locking tab 332overlaps a portion of the locking ring 314 and may be held in place by afastener 334.

FIGS. 6A and FIG. 6B show end views of the alignment assembly 502 andthe forward bulkhead device 310, respectively. The alignment ring 504has a central opening 602 through which the forward bulkhead device 310is located. This provides an opening so that the forward connectorinsert 308 can match up with the aft connector insert 208. The alignmentassembly 502 is aligned to the forward bulkhead device 310 using thenotched key 508 on the alignment assembly 502 and a keyway 604 on theforward bulkhead device 310. See FIG. 7 .

FIG. 8 shows an end view of the aft bulkhead device 206. The aftbulkhead device 206 has a plurality of alignment holes 802 thatcorrespond to the alignment pins 506 on the alignment assembly 502. Thealignment assembly 502 then aligns the aft bulkhead assembly 202 and theforward bulkhead assembly 302 through the alignment pins 506 that are inthe alignment ring 504.

Referring again to FIG. 4 , the aft bulkhead assembly 202 and theforward bulkhead assembly 302 mate together to form a completedconnector 120 (Bootable Bulkhead). Through the mating of the aftbulkhead assembly 202 and the forward bulkhead assembly 302; theconnector 120 preserves radial alignment between modules; passes tensileloads between modules; passes optical and electrical signals betweenmodules; and provides an environmental seal at the mating junction.Because the aft bulkhead assembly 202 is not bootable, the forwardbulkhead assembly 302 is pulled into the flexible hose 108 first.

An additional feature of the present disclosure is the female clevis 210and the female clevis 306 at the ends of the aft bulkhead assembly 202and the forward bulkhead assembly 302, respectively. FIG. 9 shows anexemplary female clevis 902 having a load end 904 and a seating end 906.Female threads 908 may be located within the seating end 906. The femalethreads 908 are preferably standard Unified Series Threads (UST). Thefemale threads 908 pass tensile loads while maintaining the geometry forbooting the forward bulkhead assembly 302.

FIG. 10 shows the tensile load path across the connector 120 (BootableBulkhead). Load is distributed radially, around the entire assembly. Thetensile load path starts from the female clevis 210 on the aft bulkheadassembly 202. Referring to the depicted figures in totality, the femaleclevis 210 passes loads to the aft bulkhead device 206 through thefemale threads 908. The aft bulkhead device 206 subsequently passes theload to the locking ring 314 which bears on the retained shoulder 328.The retained shoulder 328 passes the load onto the forward bulkheaddevice 310.

Finally, the female clevis 306 on the forward end of the forwardbulkhead assembly 302 takes the load. Both female clevises 210, 306 areconnected to internal strength members in the flexible hose 108 to carryloads in the module 102 along with load sharing across the flexible hose108.

FIG. 11 is a flow chart illustrating an exemplary method of assembling atowed hydrophone array module. At step 1102, an elongated sleeve havinga first end and a second end is provided. The elongated sleeve may be aflexible tube made from an elastomer or plastic and may be reinforced,such as with Kevlar™ fibers or other suitable fibers. At step 1104, apre-tube assembly is provided. The pre-tube assembly includes aplurality of hydrophones and a harness connected to the hydrophones. Theharness has a first connector insert connected to a first end of theharness and a second connector insert connected to a second end of theharness.

At step 1106, the first connector insert is inserted into a forwardbulkhead device. The forward bulkhead device is part of a forwardbulkhead assembly, which also includes a first coupling. At step 1108,the first coupling is connected to the first end of the elongatedsleeve. At step 1110, the elongated sleeve is inflated and the forwardbulkhead device is passed through the elongated sleeve from the secondend toward the first end, at step 1112. Responsive to the forwardbulkhead device reaching the first end of the sleeve; the forwardbulkhead device is sealed onto the first coupling, at step 1114. At step1116, second coupling is connected to the second end of the elongatedsleeve. The second coupling includes an aft bulkhead assembly. At step1118, a linear array is formed by connecting the forward bulkheadassembly of one module to the aft bulkhead assembly of an adjacentmodule.

It will be understood that many additional changes in the details,materials, steps and arrangement of parts, which have been hereindescribed and illustrated in order to explain the nature of theinvention, may be made by those skilled in the art within the principleand scope of the invention as expressed in the appended claims.

The invention has been described with references to specificembodiments. While particular values, relationships, materials, andsteps have been set forth for purposes of describing concepts of thepresent disclosure, it will be appreciated by persons skilled in the artthat numerous variations and/or modifications may be made to theinvention as shown in the disclosed embodiments without departing fromthe spirit or scope of the basic concepts and operating principles ofthe invention as broadly described. It should be recognized that, in thelight of the above teachings, those skilled in the art could modifythose specifics without departing from the invention taught herein.

What is claimed is:
 1. A hydrophone module comprising: a locking ring; aflexible hose; a housing tube as an elongated sleeve having a first endand a second end; a pre-tube assembly located in said housing tube, saidpre-tube assembly including a plurality of hydrophones and a harnesswith a first end and a second end with a first connector insertconnected to the first end of said harness and a second connector insertconnected to the second end of said harness, said harness operationallyconnected to said plurality of hydrophones; a forward coupling sealingthe first end of said elongated sleeve; a forward bulkhead deviceincluding o-ring grooves around a periphery to contain sealing o-ringsand containing a first connector insert connected to the first end ofsaid harness and capable of securing wiring as well as optical fibersand a female clevis capable of securing internal strength memberstherein and a sealing sleeve including o-ring grooves around a peripheryof said sealing sleeve to contain sealing o-rings with said sealingsleeve capable of being pushed over an outside of said forward bulkheaddevice after said sealing sleeve has been pulled through said flexiblehose and with said sealing sleeve capable of accommodating a lockingring wherein an outer diameter of said forward bulkhead device issmaller than an inner diameter of said first coupling; an aft couplingconnected to and sealing the second end of said elongated sleeve withsaid aft coupling including an aft bulkhead device with a plurality ofalignment holes and o-ring grooves around a periphery of said aftbulkhead device to contain sealing o-rings, an aft connector insertconnected to the second end of said harness and capable of securingwiring as well as optical fibers and a female clevis capable of securinginternal strength members therein; an alignment assembly including anotched key, said alignment assembly being mateable with said aftbulkhead device to align said forward connector insert with said aftconnector insert on said notched key; a locking ring capable ofconnecting said forward bulkhead device with said aft bulkhead device;and a retained shoulder threaded onto said forward bulkhead device toensure proper alignment of said forward bulkhead assembly with said aftbulkhead assembly and to provide a bearing surface for said locking ringand said alignment assembly; wherein said forward bulkhead device iscapable of being booted through said forward coupling and said flexiblehose when said flexible hose is inflated; wherein a portion of said aftbulkhead device is capable of being fitted within said locking ring anda portion of said aft connector insert is capable of fitting within saidforward bulkhead device such that a distal end of said aft connectorinsert can form a mating junction at a distal end of a forward connectorof another hydrophone module.
 2. The hydrophone module according toclaim 1, said alignment assembly further comprising: an alignment ringhaving a central opening so that said forward connector insert can matchup with said aft connector insert and said alignment ring having aplurality of apertures with said alignment ring surrounding said firstconnector insert; and at least one alignment pin extending perpendicularto said alignment ring toward said aft bulkhead device such that said atleast one alignment pin corresponds to the alignment holes of said aftbulkhead device thru said plurality of apertures.
 3. The hydrophonemodule according to claim 2, wherein said aft bulkhead device includesat least one alignment hole corresponding to at least one alignment pin.